You should check out Printout Desinger in the App store. Our solutions allows you to create custom printouts with the exact fields that you need. Check it out here: https://apps.shopify.com/printout-designer
Out team is more than happy to guide you through the process...
Please see our articles on how to include ABN of your online store and how to capture ABN numbers from your customers.
When using Sufio, all these numbers are then automatically included on your invoices that are compliant with the Australian legislation.
Hope this helps! If you need any further help just let me know.